Solid-liquid phase equilibria of the Gaussian core model fluid.

Area of Science:

• Computational physics and chemistry.
• Thermodynamics and statistical mechanics.

Background:

• The Gaussian core model is a fundamental system for studying phase transitions.
• Reentrant melting, where a solid melts and then resolidifies upon heating, presents unique challenges in phase equilibria determination.

Purpose of the Study:

• To precisely determine the solid-liquid phase equilibria of the Gaussian core model.
• To apply the Gibbs-Wang-Tang-Sadus (GWTS) algorithm to a fluid system exhibiting reentrant melting for the first time.

Main Methods:

• Utilizing the Gibbs-Wang-Tang-Sadus (GWTS) algorithm, which integrates equilibrium and nonequilibrium molecular dynamics simulations.
• Comparing results with established Monte Carlo simulations and solid free energy calculations.

Main Results:

• The GWTS algorithm enabled more precise calculation of the Gaussian core model's phase envelope.
• Excellent agreement was observed between GWTS results and Monte Carlo simulations for both low-density and high-density (reentrant melting) regions.
• The coexistence point of equal-density solid and liquid phases was determined with high accuracy.

Conclusions:

• The GWTS algorithm is effective for accurately determining phase equilibria, including complex scenarios like reentrant melting.
• This study validates the GWTS algorithm's applicability to challenging fluid systems.
• Precise determination of phase envelopes aids in understanding fundamental material properties.